An air intake system for an aircraft engine includes an air duct having an inlet port to provide fluid communication between the inlet port and the engine and a removable air filter assembly configured to interface with the inlet port of the air duct and a skin of the aircraft. The air filter assembly includes an air filter frame having an outer wall and an inner wall, the outer wall of the air filter frame forming an air filter slot. The air filter assembly also includes a bypass door forward of the air filter slot and an air filter insertable into the air filter slot. The bypass door is movable between a closed door position and an open door position, air flowing to the inlet port of the air duct via the air filter in the closed door position and bypassing the air filter in the open door position.

A pipe unit coupling structure includes a first member in which a first hole is formed, a second member including a pipe unit which is coupled to the first member by being inserted into the first hole, and a third member coupled to the second member by a coupling unit. The second member has an inclined surface formed at a tip of the pipe unit. The inclined surface is configured in such a manner that, when the inclined surface is pressed against the first member when the pipe unit of the second member is inserted into the first hole of the first member in a state where the second member and the third member are coupled to each other, a force is applied from the second member to the third member at the coupling unit, in a direction opposite to a direction of separation of the second member.

A pipe unit coupling structure includes a first member in which a first hole is formed, a second member including a pipe unit which is coupled to the first member by being inserted into the first hole, and a third member coupled to the second member by a coupling unit. The second member has an inclined surface formed at a tip of the pipe unit. The inclined surface is configured in such a manner that, when the inclined surface is pressed against the first member when the pipe unit of the second member is inserted into the first hole of the first member in a state where the second member and the third member are coupled to each other, a force is applied from the second member to the third member at the coupling unit, in a direction opposite to a direction of separation of the second member.

A watercraft includes a hull, an engine compartment defined at least in part by the hull, an engine disposed in the engine compartment, an air intake conduit fluidly connected to the engine, an air filter fluidly connected to the air intake conduit, and a shroud connected to an inlet end of the air intake conduit located in the engine compartment. The shroud has an open end and a closed end. The open end is open to flow of air therethrough and the closed end is closed to flow of air therethrough. The shroud has a sidewall extending between the closed and open ends. The shroud is oriented such that the open end is disposed rearward of the closed end. Noise exiting the inlet end of the air intake conduit and the air filter is reflected generally rearward by the shroud. An engine assembly for a watercraft is also disclosed.

A watercraft includes a hull, an engine compartment defined at least in part by the hull, an engine disposed in the engine compartment, an air intake conduit fluidly connected to the engine, an air filter fluidly connected to the air intake conduit, and a shroud connected to an inlet end of the air intake conduit located in the engine compartment. The shroud has an open end and a closed end. The open end is open to flow of air therethrough and the closed end is closed to flow of air therethrough. The shroud has a sidewall extending between the closed and open ends. The shroud is oriented such that the open end is disposed rearward of the closed end. Noise exiting the inlet end of the air intake conduit and the air filter is reflected generally rearward by the shroud. An engine assembly for a watercraft is also disclosed.

A straddled vehicle includes an air cleaner and a resonator. The air cleaner includes an air cleaner case, an air-cleaning element arranged inside the air cleaner case, and a duct that is attached to the air-cleaning element. At least a portion of the duct is arranged inside the air cleaner case, and the duct guides the air toward the air-cleaning element. The resonator has an outer wall arranged around the duct. The duct and the outer wall together define at least a portion of a resonance chamber of the resonator.

A straddled vehicle includes an air cleaner and a resonator. The air cleaner includes an air cleaner case, an air-cleaning element arranged inside the air cleaner case, and a duct that is attached to the air-cleaning element. At least a portion of the duct is arranged inside the air cleaner case, and the duct guides the air toward the air-cleaning element. The resonator has an outer wall arranged around the duct. The duct and the outer wall together define at least a portion of a resonance chamber of the resonator.

An air cleaner assembly can contain an air filter element to filter contaminant material out of an air stream. In some examples, the air cleaner assembly includes a housing with an integrated noise suppression chamber for supplying air to a downstream compressor. The housing forms a cavity into which an air filter element is inserted. Contaminated air enters the housing and passes through the air filter. Filtered air can discharge from the housing through a first opening supplying air to a combustion engine and a second opening supplying air to a compressor. Air supplied to the compressor passes from the interior of the housing containing the filter element and through the integrated noise suppression chamber before being discharged. The acoustic energy released by the filtered air stream exiting the air cleaner assembly may be reduced by passing through the noise suppression chamber.

An air cleaner assembly can contain an air filter element to filter contaminant material out of an air stream. In some examples, the air cleaner assembly includes a housing with an integrated noise suppression chamber for supplying air to a downstream compressor. The housing forms a cavity into which an air filter element is inserted. Contaminated air enters the housing and passes through the air filter. Filtered air can discharge from the housing through a first opening supplying air to a combustion engine and a second opening supplying air to a compressor. Air supplied to the compressor passes from the interior of the housing containing the filter element and through the integrated noise suppression chamber before being discharged. The acoustic energy released by the filtered air stream exiting the air cleaner assembly may be reduced by passing through the noise suppression chamber.

An air cleaner assembly includes an air cleaner body into which air flows from outside, an air cleaner cover which is fastened to the air cleaner body and from which the filtered air is exhausted, and an air filter installed between the air cleaner body and the air cleaner cover to filter foreign material, and which is installed at an intake pipe introducing air into an engine from outside, where a diffuser guiding the exhaust of the filtered air is installed at the air cleaner cover; and the supporting member, which supports an outside surface of the diffuser on the air cleaner body and the air cleaner cover and allows air to pass in a longitudinal direction of the diffuser, is installed at the air cleaner body and the air cleaner cover, respectively, thereby supporting the diffuser and tuning the intake sound by the air flowing therein.